If you find that you're spending almost all your time on theory, start turning some attention to practical things; it will improve your theories. If you find that you're spending almost all your time on practice, start turning some attention to theoretical things; it will improve your practice.

Donald Knuth, quoted in: Arturo Gonzalez-Gutierrez (2007) Minimum-length Corridors: Complexity and Approximations. p. 99